[17.5-6] codominance, multiple alleles, and sex-linkage
No description yet. This curated deck is ready for daily study.
Card preview (10)
describe the shorthand for codominant alleles (good luck)
• put them as superscripts on a letter that represents that gene eg. CᴿCᵂ • cross these in normal 2x2 punnett square
describe the possible genotypes for each blood type
• A = IᴬIᴬ or IᴬIᴼ • B = IᴮIᴮ or IᴮIᴼ • AB = IᴬIᴮ • O = IᴼIᴼ
what happens when there are multiple alleles?
• only 2 can be present in an individual at any one time • some alleles are codominant and some are recessive to both
who can fathers pass sex-linked alleles on to?
daughters but not sons
who can mothers pass sex-linked alleles on to?
both sons and daughters
describe the differences between how sex-linked recessive traits are expressed
• in females, these traits will be expressed only in the homozygous condition • any male receiving the recessive allele from his mother will express the trait • feamles can be carriers for recessive alleles but males cannot
what are some examples of sex-linked conditions?
• colour blindness • duchenne muscular dystrophy • haemophilia • hunter syndrome • menkes disease
why does sex-linkage occur?
• female = XX, male = XY • no homologous portion on Y chromosome that might have dominant allele
describe the nomenclature for sex-linked punnet squares
XᴬXᵃ, XᵃY⁻
pedigree charts
• male = square • female = circle • shading = presence of characteristic